Many zoos have predatory animals such as lion, tigers, pumas, panther, lynxes, wolves, hyenas etc. Often these animals spend a large part of the day sleeping or resting. Often the animals get very little exercise, and the only exercise that these animals get is a standard walk which is repeated over and over. Typically, the standard walk is located in front of the fence.
This situation is very remote from a natural environment, in which predators have to hunt for food and automatically stay fit as a result of the hunt.
The lack of exercise is bad for the physical and mental health of the animals, and also tends to make the spectacle somewhat boring for visitors of the zoo. The animals which are most impressive in physique are often the most boring to watch.
In the past, certain exercise systems have been used for predators. One system was derived from dog races and comprised a rail along which a bait was moved at high speed. However, in a zoo the animals do not have a predefined starting position as in a dog race. It was found in practice that the animals were smart enough to understand that the bait would stop moving at the end of the rail. The animals simply waited at the end of the rail to grab the bait.
Another system is known from U.S. Pat. No. 3,312,195. This system is cumbersome, relatively slow and not very sturdy. The movements of the bait are quite limited. The system is in particular not very suitable for large cats such as lion.
Another system is known from U.S. Pat. No. 6,314,913. This is a gadget which is suitable for pets, but completely unfit for zoos and large predators.